BEYOND Study: A Multicentre, Prospective, Observational Study of Real-world Treatment Patterns and Outcomes of Trastuzumab Deruxtecan in Patients With HR Positive, HER2-low or Ultra-low Metastatic Breast Cancer Previously Treated With Endocrine Therapy

A Multicentre, Prospective, Observational Study of Real-world Treatment Patterns and Outcomes of Trastuzumab Deruxtecan in Patients With HR Positive, HER2-low or Ultra-low Metastatic Breast Cancer Previously Treated With Endocrine Therapy

BEYOND study is designed to generate the first real-world data from GCC countries on the patient characteristics, treatment patterns, survival outcomes, and safety of T-DXd in patients with HRpositive,HER2-low or HER2-ultralow mBC previously treated with ET. The evidence generated will help to optimise treatment strategies, inform clinical guidelines, and ultimately improve outcomes for patients with mBC across the region.

Inclusion Criteria:

• -Female patients aged ≥18 years old at the time of T-DXd initiation
• Patients with a confirmed histological or cytologically based diagnosis of HR-positive mBC.
• Patients who were classified as HER2-low or HER2-ultralow mBC confirmed by the closest locally obtained HER2 test prior to or on the index date, and who meet the following definitions:
• HER2-low status defined as IHC scores 1+ and 2+ without ISH gene amplification based on the pathology report.
• HER2-ultralow status defined as IHC 0 with membrane staining based on the pathology report.
• Patient who received at least one prior line of ET (± targeted therapy) in the metastatic setting.
• Patients who are chemotherapy-naïve in the metastatic setting.
• Patients who initiated T-DXd up to 30 days before the signature of the ICF. The decision to initiate T-DXd must be made independently by treating physicians as part of routine clinical practice.
• Patients are willing to sign the written ICF, indicating that they understand the purpose of the study and procedures required for participation.

Exclusion Criteria:

• -Patients with a history of other malignancies, other than basal cell carcinoma of the skin and squamous cell carcinoma of the skin.
• Patients who received prior chemotherapy in the metastatic setting.
• Patients with Eastern Cooperative Oncology Group (ECOG) status ≥2 or missing ECOG status at the time of initiation of T-DXd (index date).
• Patients with a history of participation in another clinical trial in the metastatic setting.
• Female patient with current or planned pregnancy, or breastfeeding.